Numerical Simulation of Flows Near and Through a Two-Dimensional Array of Buildings.

摘要

A numerical simulation has been performed of turbulent flow near and through a two-dimensional array of rectangular buildings (bluff bodies) in a neutrally stratified background flow. The model used for the simulation was the steady-state Reynolds-averaged Navier-Stokes equations with an isotropic, linear eddy viscosity formulation for the Reynolds stresses; and, the eddy viscosity was determined using a high-Reynolds number form of the kappa-epsilon turbulence-closure model with the boundary conditions at the wall obtained with the wall-function approach. The resulting system of partial differential equations along with the concomitant boundary conditions for the problem was solved using the SIMPLE algorithm in conjunction with a non-orthogonal, collocated, cell-centered, finite volume procedure. The predictive capabilities of the numerical simulation of urban flow are validated against a very detailed and comprehensive wind tunnel data set. Vertical profiles of the mean streamwise and vertical velocities and the turbulence kinetic energy are presented and compared to those measured in the wind tunnel simulation. In addition to the comparison between modeled and measured results, the numerical simulation is used to aid in the interpretation of certain features of the flow observed in the wind tunnel simulation. it is found that the overall performance of the model is good---most of the qualitative features in the disturbed turbulent flow field in and near the building array are correctly reproduced, and the quantitative agreement is also generally fairly good (especially for the mean velocity field). The underestimation of the turbulence energy levels may arise from the inability of the model to capture the subtle effects of secondary strain, especially those associated with curvature, on the turbulence.